One vertex per element, one color per generator, with an edge from x to x·s.
(9,10)(11,12)(13,17)(14,15)(16,19)(18,20)(21,22)(23,24)(25,26,32,36)(27,34,28,33)(29,35,30,31)(37,40,38,39)(1,2)(3,4)(5,6)(7,8)(10,15)(12,16)(17,22)(20,23)(25,27,32,28)(26,33,36,34)(29,38,30,37)(31,39,35,40)(2,6)(4,7)(13,21)(17,22)(18,24)(20,23)(25,28,32,27)(26,34,36,33)(29,38,30,37)(31,39,35,40)(9,11)(10,16)(12,15)(13,18)(14,19)(17,23)(20,22)(21,24)(25,29,32,30)(26,31,36,35)(27,37,28,38)(33,40,34,39)(1,3)(2,7)(4,6)(5,8)(9,12,14,16)(10,11,15,19)(13,20,21,23)(17,18,22,24)(25,30,32,29)(26,35,36,31)(27,38,28,37)(33,39,34,40)(1,4,5,7)(2,3,6,8)(9,13,14,21)(10,17,15,22)(11,18,19,24)(12,20,16,23)(25,31,32,35)(26,29,36,30)(27,39,28,40)(33,38,34,37)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.